# Homework Help: Circular Motion of a roller coaster

1. Oct 7, 2007

### aligass2004

1. The problem statement, all variables and given/known data

The passengers in a roller coaster car feels 55% heavier than their true weight as the car goes through a dip with a 24m radius of curvature. What is the car's speed at the bottom of the dip?

2. Relevant equations

3. The attempt at a solution

I have no clue as to how to start this problem.

2. Oct 8, 2007

### Hootenanny

Staff Emeritus
Start by drawing a free-body diagram and examining the forces acting on the car. What do you know about the net force of an object travelling in a circle?

3. Oct 8, 2007

### aligass2004

The forces acting on the car are weight and the normal force. Also, the velocity is perpendicular to the force pushing inward, which is why the object remains circular.

4. Oct 9, 2007

### Hootenanny

Staff Emeritus
Correct! So, do you know a relationship between force, velocity and radius for an object travelling in a circular path?

5. Oct 10, 2007

### aligass2004

I have no idea.

6. Oct 10, 2007

### queenyv2005

use the equation hmg=mg + mv^2/r. for example my percentage was 35% and my radius was 30m. so .35(9.8)= v^2/30 and solve for v